Braking mechanism



Sept. 24,1940. BJDICK' 9 9 BRAKING MECHANISM 4 Filed July 31, i939INVENTOR I BURNS DICK ATTORNEY J ofthe'drum- Patented Sept. 24, 1940UNITED STATES. PATENT oi-"r cg t Burns Dick, Ferguson, Mo., assignor toWagner Electric-Corporation, .st houis, Mo., a corporation of DelawareApplication July 1939, Serial No. 281,511

My invention relates to braking mac and has for oneof its objects toprovide an improved brake of the type having a lining carrying bandextending over substantially 360 degrees A more specific object of myinvention is to provide, in a band brake having associated therewith apressure applying lever connected to the band and pivotally mounted onthe support,

1 means for so automatically adjusting the mounted end of the lever thatwear of the lining will be compensated for and the distribution ofpressure on the band by the lever will not be altered during the life ofthe lining.

Other objects of my invention will become ape parent from the followingdescription takenin connection with the accompanying drawing in 4- whichFigure, 1 is a side vie'w, partly in section,

of a brake assembly embodying my invention;

Figure 24s a cross sectional view taken on the line {-2 of Figure 1showing the mounting of the pressure applying lever; Figure 3 is a viewtaken on the lined-4 of Figure 2; and Figure 4 is a cross-sectional viewtaken on the line 1-4 of Figure l. 1

Referring to the drawing indetail, the numeral I indicates a brake drumwhich is fixed to the rotative element (not shown) to be braked,

and 2 the support for mounting the brake within the drum, said supportbeing secured to a fixed member. The drum is enclosed by a dustexcluding plate 3 secured'to the support 2. Within thezdrum is asubstantially 360 degree brake band 4 provided with a continuousfriction linm 5. The ends of the band are provided with reinforcingmembers I and '8 which cooperate with the oppositely movable pistons(not shown) of an actuating fluid motor 9 of well-known con struction.

The support 2 is formed with an arm to and mounted thereon at one of itsends is an arcuateshaped lever ll extending over and contacting asubstantial arc of the band, the other end of said lever being securedto the band by having a portion l2 thereof extending into a slot l3 inthe band. The means for. mounting the end of the lever II on the supportarm Ill comprises an anchor pin I4 carried by said am and upon which ispivotally mounted a block l5. The end of the lever is notched to form anabutment surface l6 and a surface l'l at right angles thereto.

A U-shaped member i8 is mounted on the end of the lever and forms, withthe notched end of the lever;@ pocket for receiving the block l5.

6 Claims. (c1. issqas) This constructionpermits the end of the lever tohave relative movement outwardly toward the drum-with respect to theblock. The pocket in which the block is positioned is slightly oversizewith respect to the block to permit the insertion 5 of a leaf Spring I9between'the block and the closed end of the U-shaped member for causingthe abutment surface It on the endof the shoe to be held in tightfrictional engagement with the cooperating surface of the block. The U-10 shaped member. is provided with oversize openings 20 to permit freerelativemovement of. the end or the shoe with respect to the pin. Theend of the shoe is held on the anchor pin by a C washer 29 engaging agroove in the inner end 15 of the pin.

The anchor'pin ll constitutes the sole anchor for the brake band whenthe drum is rotating will cause the band to swing the lever outwardly 1toward the drum and whereby the lever will ap- 25 ply a radial pressureto the band over that portion of the band with which it contactsQ It isthus seen that e self energizing actionof the band produces anadditional pressure on the rear portion of the band by means of thelever which 30 will increase the total braking torque of the band overthat of a band in which the band is anchored at its intermediate pointor at one end. The force ,acting on .the lever during brake applicationwill also cause the mounted end of the lever to be forced outwardlytoward the drum since the plane of contact between the abutment surfacel6 and the block is at such an angle I that there will be a force actintoward the drum.- J

This forcis sufllcient to overcome the frictional resistance created bythe spring i9 between surface l6 and the block. It is to be noted,however, that the spring does not-inany way 're-' strain free pivotalmovement of the lever. Thus the lever can have its free swingingmovement as the band is applied and released from the drum and thefriction created by the spring will not be afiected. As the brakelinin'gi of the band wears, the mounted end of the lever-will beautomatically adjusted toward the drum and this new adjusted positionwill always be maintained by the spring I9 which is 'of such strength asto create suilicient friction between the abutment surface I6 and theblock that the disena gagement of the band from the drum will not movethe mounted end of the lever from its new adjusted position. The brakeband, when released, will cause the lever to pivot in a clockwisedirection about its mounted end and this pivotal movement will be suchas to permit the freeing of the band from the drum. It is to be noted inthis respect that a substantial portion of the lever adjacent itsmounted endis not in contact with the band.

There is. also provided a spring 2| connected between the reinforcingmembers I and 8 on the ends of the band for retracting the ends of theband when the fluid motor is released. A suitable automaticallyadjustable stop means 22 coment for wearof the lining throughout theentire life of the lining. The retractile spring 2| will not in any wayaffect the adjustment of the mounted end of the lever since the frictionbetween the abutment surface and the block is great enough to maintainthe adjustment against the pull of this retractile spring.

Being aware of the possibility of modifications in the particularstructure herein described without departing from the fundamentalprinciples of my invention, I do not intend that its scope be limitedexcept as set forth by the appended claims.

Having fully described my invention, what I claim as new and desire tosecureby Letters Patoperates with the reinforcing member I to limit entof the United States is:

the "distance this end of the bandcan be -re- 1. In braking apparatus,the combination of a tracted from the drum, support, a brake drum, afriction device adapted in order that there may be an anchor for the tohave its'ends expanded to engage t W the band when the. drum is rotatingin the direction drum. a l v r m n e at e n n the pp opposite thatindicated by the arrow the support adjacent the friction device for bothpivotal move- 2 is formed with a downwardly extending arm 23 me t a dadjustment toward the drum and conand mounted on this arm i pin '24 towhich nected at its other end to an intermediate porissecured a block 25f i ti ith the tion of the friction device, an intermediate poradjacentend of the lever ll; Thus, when the tion of said lever contacting thefriction device band is applied with the drum .rotating in the and app yng 91 radial Pressure to Substantial direction opposite that indicatedby the arrow, arc thereof when said friction device is engaged the leverwill engage the block 25 and anchor the band at its intermediateportion. Under these circumstances the band will act as an ordinary bandwhich is anchored only at its center.

In order that the band may" be actuated by an auxiliary means, I havealso employed the block 25 as part of an auxiliary actuating mechanism.The block is formed with a cam surface 26 and the pin upon which it ismounted is capable of being rotated by means of a lever 21 and a rod 28which leads to some remote actuating member. n

When the rod 28 is moved to the left, as seen in Figure 1, the camsurface on the block will apply a. pressure to the end of lever H andforce the band into engagement with the drum.

with the drum, said-mounting for the end of the lever comprising partshaving abutting surfaces capable of-refative sliding movement in aselected plane for. permitting said end of the lever to be automaticallyadjusted toward the drum by force The band brake construction justdescribed adjacent the friction device for both pivotal has been foundto be eflicient in operation and movement and adjustment toward the drumand easily controllable. The association of the lever connected at itsother end toan intermediate H with the band in the manner shown, resultsportion of the friction device, the intermediate n t e band having eat tq Output in portion of said lever contacting the friction dethe forwarddirection of rotation. Also, this lever vice and applying a radialpressure to a subpermits the band to be easily controllable sincestantial arc thereof when said friction device is the amount of radialpressure createdby the engaged with the drum, said mounting for thelever will depend upon the force with which the end of the lever.comprising abutment means carforward section of the band; is applied tothe ried by the support for preventing circumferendrum by the fluidmotor. There will always be a tial movementof thelever and other meansperdirect relationship between the input force of the mitting the end ofthe lever to move toward the band and the torque output of the brake.Also, the band, when it has associated therewith lever ll, does not tendto become stuck to the drum when the fiuid motor is released.

The special mounting for the end of the lever I 60 permits this end ofthe lever to be automatically adjusted toward the drum as the liningwears. Thus the relationship between the lever and the band will alwaysbe maintained the same and the distribution of pressure on the band bythe lever will be unaltered as the lining wears. If the drumautomatically by force effective on the;

lever during braking application when the brake lining thickness of thefriction device adjacent mounted end of the lever were not automaticallyE brake hand Provided With lining f adusted in the manner shown, the arcof contact adapted to have its ends e b d to. en between the lever andthe band would decrease as with the dru 910118158 lever ted a One thelining became worn and the effectiveness of e d 0 t e ppfl adj t e end ot e band the lever would be decreased. By having the for both pivotmovement and j ent tomounted end of the lever adjustable, this are ofward the drum and connected at its-other end contact will always bemaintained the same to an intermediate portion of theband, saidthroughout the life of the lining. Also, by havlever contacting the bandand pp g a rad a ing the mounted end of the lever automaticallypressureto a substantial arc thereof when said adjustable, it isunnecessary to make anyadjustband is engaged with the drum. and saidmounteffective on the lever during braking application ing for the endof the lever comprising parts having abutting surfaces capable ofrelative sliding movement in a selected plane for permitting said end ofthe lever to be automatically adjusted toward the drum by forceeffective on the lever during braking application and when the liningadjacent said mounted end of the lever is reduced by wear, vand frictionmeans preventing the end of the lever from returning to a positionoccupied prior to an adjustment.

4. In braking apparatus, the combination of a support, a brake drum, asubstantially 360 degree brake band provided with lining and adapted tohave its ends expanded to engage itwith the drum, an arcuate levermounted at one end on the support adjacent one end of the band for bothpivotal movement and adjustment toward the drum and connected at itsother end to an intermediate portion of the band, said lever contactingthe band and applying a radial pressure to a substantial arc thereofwhen said band is engaged with the drum, said mounting for the end ofthe lever comprising parts having relative rotative movement forpermitting pivotal movement of the lever and also parts having abuttingsurfaces capable of relative sliding movement in a selected plane forpermitting said end of the lever to be automatically adjusted toward thedrum by force effective on the lever during braking application and whenthe lining adjacent said-mounted end of the lever is reduced by support,a brake drum, a friction device adaptedto have its ends expanded toengage it with thedrum, a lever mounted at one end on the supportadjacent the friction device for both pivotal movement and adjustmenttoward the drum and 45 connected at its other end to an intermediateportion of the friction device; an intermediate portion of said levercontacting the friction device and applying a radial pressure to asubstantial arc thereof when said frictionudevice is engaged withthedrum, said mounting for the end of the lever comprising an anchor pincarried by the support, a member provided with a plane surface andmounted on the pin for pivotal movement only, means forming a planeabutment surface on the-lever for engaging the plane surface on themember and permitting the end of the lever to'move toward the drum andrelatively to,

the member by force effective on the lever during braking applicationwhen the friction device adjacent the mounted end of the lever isreduced by wear, and means independent of the anchor pin and cooperatingwith the lever and the member for frictionally maintaining the end ofthe lever in adjusted position with respect to the member.

6. In braking apparatus, the combination of a support, a brake drum, asubstantially 360 degree band provided with lining and adapted to haveits ends expanded to engage it with the drum, an arcuate lever mountedat one 'end on the support adjacent one end of the band for' bothpivotal movement and adjustment toward the drum and connected at itsother end to an intermediate portion of the band, said lever contactingthe band and applying a radial pressure to a substantial arc thereofwhen said band is engaged with the drum, said mounting for the end ofthe lever comprising an anchor pin carried by the support, a. blockmounted on the pin for pivotal movementonly, means forming a slot in theend of the lever for receiving the block and permitting a flat surfaceof the slot to engage a flat surface of the block whereby the end of thelever will move toward the drum and relatively to the block by forceeffective on the lever during braking application when the liningadjacent-the mounted end of the lever is reduced by wear, and a springcarried by the lever for forcing the flat abutment surface of the leverinto frictional engagement with the flat surface of the block andmaintaining the end of the lever in adjusted position with respect tothe block.

' BURNS DICK.

